Many processes require, or would at least benefit from, on-line monitoring of the chemical composition and/or other parameters of gaseous suspensions involved. Such in-situ analysis entails a number of significant advantages over other techniques (e.g., the analysis of conversion products), particularly in that all of the problems associated with sampling and sample handling are inherently eliminated; it also permits dynamic monitoring of chemical and/or physical changes that occur during the course of combustion, pyrolysis, and other types of reactions.
As far as is known, very few (if any) of the forms of instrumentation heretofore available are useful or satisfactory for the on-line analysis of particle streams (as used herein, reference to "particles" is to be understood to include liquids and solids, as well as mixed phases). In particular, it is not believed that any such instrumentation is capable of resolving size, temperature, number density and/or quantitative chemical composition for particle-containing gaseous streams, especially in a reactive environment.
It is of course well known to utilize electromagnetic radiation for a variety of analytical purposes, as evidenced by the body of prior art patents issued in the United States. For example, in Bertrand U.S. Pat. No. 2,333,762 an analytical technique is disclosed in which the intensity of radiation is used to determine the solid content of a gaseous medium. A temperature measurement system, operating upon absorbed and emitted radiation, is described in Tandler et al Pat. No. 2,844,032, and in Pat. No. 2,878,388 Bergson discloses a system for analyzing gases by measuring the absorption of radiant energy.
Seelbinder Pat. No. 3,724,951 and Riggs Pat. No. 3,743,430 both involve techniques for making aerosol opacity determinations, based upon transmitted radiation, and Snowman Pat. No. 3,588,496 teaches radiation absorption analysis apparatus for identifying samples of gases, aerosols and liquids. Each of the following patents uses irradiation scattering as a basis for detecting and/or analyzing aerosols or smokes: Hilsum Pat. No. 3,317,730, Charleson et al Pat. No. 3,700,333, Lepper, Jr. Pat. No. 3,787,122, and Mueller Pat. No. 3,882,477. In Patent No. 4,017,193, Loiterman describes apparatus for measuring the transmittance of a gaseous medium carrying particulate matter through a conduit, and Suga Pat. No. 4,021,713 discloses apparatus for the sequential measurement of radiation transmitted through smoke.
Neugroschel Pat. No. 3,703,337 discloses an analytical processor capable of handling at least two characteristics of the specimen, simultaneously measuring and converting them for digital print out. Vanesse Pat. No. 4,095,899 concerns a technique for performing Fourier spectroscopy. In Cashdollar et al Pat. No. 4,142,417, an infrared pyrometer is used to determine radiation emitted from a gas and/or particle, with temperatures being determined by correlation of the radiation data to black-body radiation curves. Kraushaar et al Pat. No. 4,304,491 discloses the use of a spectrometer to detect both dispersed and undispersed irradiation for IR imaging.
Cells and associated devices, used for spectroscopic analysis of samples, are described in Gaglione Pat. No. 3,478,206, Sole et al Pat. No. 3,631,237 and Witte Pat. No. 3,730,630. Surface temperature measuring apparatus is taught by Brandli et al in Pat. No. 3,924,469, and a photometer/detector/amplifier arrangement, for use in automatic analysis apparatus, is shown in Atwood et al Pat. No. 4,014,612.
In Stein Pat. No. 4,440,510, a system is disclosed for pyrometric gas temperature measurement, carried out by adjusting and comparing the physical temperature of a black-body with the radiation temperature thereof measured through the gas. A spectrometric method for determining the size of metal particles in oils is taught in Kauffman et al Pat. No. 4,448,887, and a method and apparatus for determining size distribution of particles, by fitting a selected parameter distribution function to scaler representations of data obtained, is disclosed in Hobbs et al Pat. No. 4,453,226.
Finally, in an article entitled "Fire Flame Radiation" (Combustion and Flame 52: 127-135, 1983), Vervisch and Coppalle discuss the use of normalized emission measurements for determining the temperature of flames containing soot.
Despite the foregoing, a need remains for means by which analyses of the sort described above can be carried out conveniently and effectively.
Accordingly, it is a primary object of the present invention to provide a novel method and apparatus by which gaseous suspensions of liquid and/or solid particles can readily be analyzed for any of a variety of physical and chemical properties.
More specific objects are to provide such a method and apparatus by which such a suspension can be analyzed either in-situ, in a reactive environment, or as a supplied sample, for determinations of particle size, temperature, number density, spectral emittance, and/or composition, in a manner that is very fast, convenient, and effective.